I'll Follow You Into The Dark
by hhmmm-shadowhunters
Summary: Isabelle had always been slightly jealous of mundanes simple lives. When she & Jace decide to go to Pandemonium one night, simply to be normal teenagers, they run into a girl named Clary & her friend Simon. They meet & things start happening, will they be able to handle this? Better than it sounds, please just check it out! :D Please tell me if you think I should continue!
1. Chapter 1

**I do not own the mortal instruments or the characters in this story unless I state otherwise. I just came up with the idea for the fanfic. **

Isabelle had always been a tad bit jealous of mundanes. Sure, she loved being a Shadowhunter. Who wouldn't? But sometimes she envied the mundanes. Their lives were so simple, so easy, compared to hers. She felt stupid for envying them. After all, she did protect them. Without her their lives would probably be a hell of a lost worse than they are.

But that didn't stop her curiosity. What was it like to be a mundane? To just go out and have fun with your friends, not having to worry about killing some demon? She wanted to know. She was determined to know. And that is why she's sneaking out of the Institute, dressed like she's going to a party. She is going to a party, technically. Pandemonium's an all age's club, so it's like a party. "What're you doing?"

Isabelle jumps, putting her hand over her mouth to keep from screaming. She may be a Shadowhunter, but that doesn't mean she doesn't get caught off guard sometimes. She sees Jace, leaning against the wall. He looks amused and interested. "Nothing," Isabelle says quickly.

"Doesn't look like nothing," Jace says, starting to walk towards her. "Are you sneaking out?"

Isabelle meets his gaze, "Maybe."

Jace smirks. Where're you going?" Isabelle sighs.

"Pandemonium," she says, meeting his gaze again. Jace's amused expression changes to a confused one.

"Why are you going to Pandemonium? We weren't planning on going tonight, there's not supposed to be that many demons," he says.

Isabelle sighs, again. "That's the point."

Jace tilts his head, his eyes lighting up, as if he's just realized what she's planning on doing.  
"Why?" he asks. "What's the point in going and pretending like you're one of them?"

"Because," Isabelle says, starting to push past him. "Just let me go, and don't tell."

"I won't tell if you let me go with you," Jace replies, already walking beside her. Isabelle simply nods, not in the mood to argue and ready to take whatever she can get.

Simon hated Pandemonium, Clary knew that. Yet he still agreed to go with her every time she asked. He's a great friend like that. Simon made stupid comments while he and Clary danced. Clary would laugh and take another sip of her drink as she continued to dance. She was pretty sure she was terrible, but she felt better dancing with Simon. He was a worse dancer than her, definitely.

"It's crowded tonight," Simon calls over the music. Clary nods her head in agreement. In just the last five minutes more than five people had bumped into her on the dance floor. Simon opens his mouth to say something else but Clary cuts him off.

"_Shit!_" she exclaims. Someone dancing by them spilled his drink on her. He mumbled an apology and went back to dancing as Clary started to push past the crowd to get something to clean herself up with. As Clary finally gets past the crowd on the dance floor and reaches the bathroom, she accidently runs into someone else. "Sorry," Clary blurts, looking up at the girl she ran into.

The girl has long black hair and is wearing a very pretty white dress; it's much prettier than the black dress Eric's new girlfriend picked out for Clary. "It's okay, hey, you okay?" the girl says, looking at Clary's dress. It now has a noticeable white spot on the hip.

"I'm fine. Some asshat just spilled their drink on me," Clary replies, looking back at the spot. The girl laughs and Clary looks back up at her.

"Oh, I'm sorry. I'm not laughing at you. It's just funny that you said 'asshat'," the girl says, smiling. "My names Isabelle, by the way," the girl adds.

"Clary," Clary replies. She smiles back at the girl. A minute later a boy walks up to them. He's tall, he has blonde hair and golden eyes.

Clary glares at him. "You," she says, poking him on his shoulder. "You spilled your drink on me!" The boy simply shrugs his shoulders.

"It was an accident," he says with a sarcastic smile. Isabelle looks horrified for a moment.

"Jace!" she exclaims. "You spilled your drink on Clary! Did you at least say sorry?"

"No, he didn't say sorry," a fourth voice replies. Clary looks over to see Simon standing behind her. "I've been looking for you. I lost you somewhere on the dance floor," he says to Clary. Clary nods as Simon steps up, so he's now standing beside her. His shoulder touches Clary's because he's standing so close.  
"This is my friend Simon. Simon, this is Isabelle. I accidently ran into her. Isabelle, this is my-" Clary freezes, looking past Jace's shoulder. There's a boy standing a few feet back. He has shockingly light hair, and his eyes appear to be all black. That shouldn't be surprising as some weird people hang around Pandemonium, but for some reason, this boy has Clary's attention. "_Simon_," Clary says a minute later.

"He's your Simon?" Jace says, making a face. Clary turns to look at him. She had forgotten Jace and Isabelle where there.

Clary ignores him and turns to back to Simon. "Do we know that boy?" she asks. Simon turns to see who Clary is referring to.

"What boy? Clary, are you okay?" Simon says, turning to look at Clary. Clary looks back to see the boy walking away. She doesn't know why, but she feels like she should follow. She just has to follow the boy, she needs to talk to him. So, instead of replying, she takes off running.


	2. Chapter 2

Simon and Jace and Isabelle all stare at each other for a moment, before Simon runs off after Clary. Isabelle goes to run after as well, but Jace pulls her back. "What do you think you're doing?" he calls over the music.

"I'm going to see what's up with Clary!" Isabelle calls back, trying to pull herself free.

"Why? She's just some mundane, she's probably drunk. Her friend will get her and she'll be fine," Jace replies with a confused expression. Isabelle shakes her head, finally pulling herself free, and runs. Jace sighs, following after.

"Dude! Stop!" Clary yells, pushing past the crowd of people. She just barely catches another glimpse of the boy as he leaves the club. Clary lets out a frustrated sigh and runs faster. When she pushes the door open, she's greeted with cold air. She sees the boy standing about fifteen feet away, and starts to walk over to him. He doesn't look at her, but he nods his head in her direction, letting her know that he's aware she's coming.

"Who are you? Why do you look so familiar?" Clary asks as soon as she's standing in front of him. He looks up at her then, and Clary can't help but gasp. His eyes are all black.

"You sure are persistent. And you're fast. But for such a small thing, that's not really surprising-" the boy starts, but cuts off when his eyes meet Clary's. He sighs. "My names Sebastian, or at least that's the name I go by."

"Clary," Clary replies.

"I know," Sebastian says with a smile.

"You know me? So that means I know you! I mean I knew I know you I just didn't know from where, but I know you!" Clary says.

"In a way, you know me. We've never officially meet," Sebastian says with a shrug.

"Clary! What the hell are you doing?" Simon yells, running towards them.

"Nu-huh, I can't see them, they can't see me," Sebastian says, shaking his head. He turns to leave, holding his hand out to Clary. "You coming?" Clary stares at Sebastian's hand. Does she go with a boy she's just meet, but feels like she's known her whole life? For some reason, Clary felt like she had to go with him. She takes Sebastian's hand.

"Goddamn it!" Simon yells, stopping just a few feet away from where Clary and the boy stood just a few seconds ago.

"What's her problem? Does she know that boy?" Isabelle asks, running up to Simon's side. Simon shakes his head.

"I've never seen that boy before in my life. Apparently Clary has, though. She's never run off with some stranger from Pandemonium."

Jace shakes his head at them, already starting to run after Clary and the boy. "Your girlfriends weird," he says, speaking again before Simon has the chance to object. "But since Isabelle got us dragged into this, I, we, can't just leave her alone to run off with some mystery boy." Isabelle and Simon start off after him.

"Her mother is going to kill me," Simon mutters. "And then I'm going to haunt Clary for the rest of her life." Isabelle almost laughs as they turn onto a crowded street. Though it's not exactly odd that the street is so crowded so late, it is annoying.

"I saw them turn down that street," Jace calls, pointing towards a street he's already running at. Simon and Isabelle follow still. Clary and the boy run into a building and Isabelle laughs a happy laugh.

"They're pretty much trapped themselves now!" she says. Jace laughs in agreement and they reach the building. Jace throws the door opens and the three of them enter, now cautious.

"Will your friends stop chasing us?" Sebastian asks, looking back at Clary over his shoulder as he walks down a hall in the building, checking each room but passing on. Clary shrugs.

"Only one of them is my friend, the other two we just met. I don't know why they'd come chasing after me," she says. Sebastian nods, opening another door. He seems to like this one and tugs on Clary's hand, telling her to follow him. "So, you never told me how you know me?" she asks as they enter the room.

"It's a long story, one we might have time for in a few moments," Sebastian replies. Clary hums in response as Sebastian squeezes her hand.

"What?" she asks her eyes still on Sebastian.

"I found what I was looking for, now, follow me. Your friends are gaining on us," Sebastian replies, pushing on the wall slightly. Clary gasps when the wall moves back, revealing another room. She allows Sebastian to lead her into the room as she hears footsteps down the hall from them.

"Why did you bring me here?" Clary asks as Sebastian closes the door that allowed them entrance into the room.

"I just want to talk to you, to see you, to know you," Sebastian replies after a moment, letting go of Clary's hand and sitting down in one of the few chairs placed around the room. Clary sits down across from him.

"Why? I don't understand, how do you know me?" she asks, reaching out and grabbing Sebastian's hand. She laces their fingers together, something she's never done with a boy but feels familiar and safe with Sebastian. Sebastian stares at their hands for a moment before replying.

"You're my sister."


End file.
